Saw-tooth grinder



Oct" 21, 1947-1 ML H. WILBERT sAw TOOTH GBINDER' Filed oct. 15, 1945.

4 sheets-sheet s INVENTOR.

MAR-UN H W IL BERT y w' *g/W ATTORNEYS. A

Oct. 21, 1947. M. H. WILBERT 2,429,300 sAw TOOTH GRINDER Filed Oct; l5, 1945v 4 Sheets-.Sheet 4 CW* CLOCKWISE Y CCW-C OU NTERCl-OCKWISE v INVENTOR. MAR-rl -N l-l-WILBEFc-l-V Fi* @Lw-N, y" VMM,

A TORNEYS.

Patented Oct. 21, l194:7

UNITED STATE Si. RATENT .f1 OEFI C E5'.

SAW-TOOTH GRINDER.

Martin-HfWilbert, San Bruna-Calif.l f

ApplicationOctoberlB, 1945, Serial Nil-622,368

Claims.4A (01976-41) An object of my invention is 'toprovide a saw` tooth grinder in which the grinding Wheelslwill exerta grinding action with the grain'of the saw blade rather than against the grain, whereby the` saw tooth will be properly'ground. .In'lthis speer..

ication Where the phrase..grindingwith..the

grain .oragainst the grain is.used. a proper definition follows: When the .grinding wheel .ape-

proaches the edge, of material frombehind l.the edge andcontacts the material beforeit reaches the edge, the material vis beinggroundvwith the. graine-fand vice versa; when the. wheel .ap-,-

proachesthe. edge from the space vand .touches the material rst at the edge, then the grinding will be'against the grain.. This samedentionapplies when usinga file; if the file is stroked... towards the edge (being sharpened) you are lingv with grain and vice versa;A if you. arelingacross the edge towardsthe material, this is against the .l

grain. K

Theprime object of this invention is .to over.

come the fault inherent in a fila/.since the ille.. Y

will only cut .in one Adirection andas a .result when you endeavorito sharpen a saw .with` a le'. you must contaotonetoothwith the .grain and.

the adjacenttooth against .the grain, the result. being that the edge being led with the'grain,...

cuts easily While the other edge onthe adjacent tooth doesznot'cut' nice. but chatterganddoes not form a sharp cutting edge nor produce sharp U points on the tooth. The tendency is to le away t the tooth beingled-.with the grainand promote unevenness of'theteethzzin'thesaw I have cor. rected this situation by. making a theoreticalfile.

which cuts with the grain on theorward stroke and on one face ofthev le; while the return...

stroke uses the -othe'nface ofthe leon the ade..

jacent tooth and again-cuts with .the grain, We now have even cutting; sharp edges and points on the teeth and therefore'even teeth. This action,

through the use `of multiple grinding wheels, will develop in detail in the specication.

A further objectl of my invention is to provide a device of the type described which makes use of the mechanism shown in my patent on a saw retoothing. machine, No. 2,300,717, issued No-- to provide va device inv which the grinding head1- ls moved so that the grinding wheels will engagev with the saw alonga .particular horizontal'line that coincides 'with' the roots of theteeth.' Im

addition, .the saww can-` be swung angularly ina swinging of .the ,saw` intodifferent angular posi;

tions .will causethe grinding .wheels .togive the proper bevel .to othesawteeth.`

Other objects land. advantages Williallllear .in.

the following. speciiication,and .the novel. fea,,

tures of the device willbe..particularlypointedn,`

out in the. appendedclaims, y

My invention is j illustrated in4 ,the accomp any: ing drawings vforminga part.. of. this application,- i

in which:

Figure 1 is a top planview. of .the..device.;

Figure `2 is a frontelevation ofthe .device when. looking inthendirjection Offfthearrows II-ILofff- Figure 1;`

Figure 3 risa transverse section, taken, along.t

the line IIIIII of Figure;1.;..

Figure 4 isja view ofthegrinding head. on` an.. enlarged scale when.. lookingjnfthe direction of the arrows IVIV'of-Figure 1,;

Figure 5 is anend viewv offthe grinder. .heaoh on still a larger scaleiwhen looking in the.direc tion of the arrows .VL-V of Figurefl; Fig-ure 6 is a schematicshowing. ofhow. .the

grinding wheels contactwith onlybneedge .Off-- a toothv at a time;

Figure 7 is an. isometricview,of..tthe.fra1ne1r supporting the grindingwheels; and .j

Figure 8 is a schematic.view.v showing how .the f saw is angularly positioned with respect tothe line of movement-takenby the grinding-wheels.. so that the' properbevelwill .be ground onV the A.

teeth. p

While I have shown onlythe preferred forms f of' my invention, it "shouldlbe" understoodthat.. various changes ormodifieationsmay bemade within the scope. of the Aappended.claims wi-thout departing. from. the spiritwand scope of. ,the fin!- s indicated 'generally' at l.A andllths'frame. has:v a

horizontal platformJQ` On the Yplatf.orm.;l, I

mount Van elongated saw supporting turntable. B fand Figure 3 illustrates'how .thecenter of*` the f turntable hasa c ylindricaLmembenZ rotatably.. mounted inA an opening 3 providedatthe center ofthe platform l.' Theturntableorsaw supporte4 eXtreme positions shown4A linesin Figure 1.

-f platform is provided with arcuate slots 4 that receive clamping bolts Whose handles E may be tightened for clamping the turntable in the desired angular position. The ends oi the slots 4 determine the limit of swing of the turntable` In Figure 3 I show shims 'I placed around the cylindrical member 2 and under the turntable for spacing the center of the turntable a predetermined distance above the adjacent portion of the platform I. The purpose of this will be 'described hereinafter. In Figures 1 and 2 I show screws B in the turntable and adapted to be adjusted for contacting the top of the platform for spacing the ends of the turntable the desired distance above the platform. The ends of the turntable are held in position by the clamping bolts 5. This arrangement gives a slight arcuate bow in a vertical plane to the turntable throughout its length. The arc of the bow can be varied by adjusting the screws 8 for altering the height of the turntable ends with respect to L the platform so that this height can be varied.

The turntable carries a saw set-up frame C. This frame has end brackets 9 secured to the ends of the turntable andthese brackets carry elongated rods IB. The rods are supported at their centers 'K by'a center bracket. A traveling saw holder D has end brackets II and I2 slidably mounted on the rods I0 .and Figure 3 shows how the travelling holder carriesV U-shaped saw-gripping members I3. In Figure 2 I illustrate how the saw gripping members I3 are supported by elongated jaws I4 and I5 and these jaws bear against opposite sides of a saw E. Clamping screws I6. force the jaws I4 and I 5 toward each other for holding the saw in proper position.

The means for advancing the saw along the set-up frame makes use of the advancing mechanism shown in my patent above referred to, In Figure 1 I show how the end bracket I2 of the traveling holder D has a slip sleeve I'I mounted on one of the rods ID. A'bell crank lever I8 is pivoted at I9 to an. extension 'of the slip sleeve and an end 29 of the lever contacts with a portion 2l of the bracket l2. Springs 22 urge the slip sleeve to the left in Figure 1 and a set screw 23 limits this movement, so that the sleeve I 'I will be disposed a predetermined distance from the adjacent surface of the portion'2 I.

If now the lever I8 is swung in a counter-clockwise direction when looking at Figure l, the slip sleeve I'I will bind upon the rod I0 and the end of the lever will' advance the bracket I2 until the .portion 24 of the bracket contacts the slip sleeve. A cable I2a and counterweight I2b lock the saw carrier normally; but pull it along the guides when lever I8 acts on the other end of the slide bar. A freeing of the lever will permit the springs 22 to move the now freed slip sleeve forward along the rod IB until the set screw 23 is again contacted. The distance between the slip sleeve and the portion 24 determines the advance of the traveling holderV D each time the lever I8 is actuated. This distance is equivalent to the length of two saw teeth.

The lever may. be actuated by any means desired, such ashydraulic, electrical, or mechanical. In the present showing, I make use of a mechanical means for operating the lever and this comprises asquare shaft 25 that is mounted in bearings 23, seeFigure 3, and 27,'see Figure 2. An arm 28 has its free end bifurcated so as to receive the free endof the-lever I8 and the arm has a bearing 29 with a squarebore that slidably receives the square shaft 25.

The square shaft is rocked by means yof a treadle 30, see Figure 3, a cord 3l connected to the turntable and passing over an idler pulley 32, and an arcuate member 33 that receives the end of the cord and is mounted on the square shaft 25. A downward movement of the treadle will cause the cord to rock the member 33, shaft 25 and arm 28 for actuating the advancing mechanism for the traveling saw holder D. The bifurcated end of the arm 28 is connected by a pin 34 to the lever I3, so that'the arm will be step-wise advanced along the square rod with the holder.

I will now describe the means for supporting the grinding head indicated generally at F, in Figure 3. ,The platform I has brackets 35 and 36 placed at the center of the platform and these brackets pivotally carry what I term sliding ways G. The sliding Ways consists of an inverted U- shaped member whose downwardly extending ends` 3l and 38 are pivotally supported at 39 and 4I! to the brackets 35 and 36. At the extremities of the ends 3l and 38 I mount clamping bolts 4I and 42 that slide in arcuate slots i3 provided in the brackets 35 an'd 33. The slots 43 permit the sliding ways to be swung about their pivots 39 and 63 into the desired angular position for a. purpose hereinafter described and then it may be locked against further swinging movement. The pivots 39 and 4B constitute additional clamping bolts that may be tightened for rigidly securing the sliding ways in place.

It should be noted that the center line M, passing through the pivots 39 and 4U also passes through the roots of the teeth which are to be formed on the saw. The grinding head F has three grinding wheels X, Y and Z, see Figure 3. The periphery of the wheels are beveled to not greater than a angle and the lower edges of the wheels will coincide with the horizontal line fill. Figure 7 shows the frame @5 of the grinding head as being shaped for supporting the wheels X and Z in a vertical plane and the wheel Y in a planethat extends atan angle thereto. The bevelled edge 53 of the wheel X tangent to the line d4 will make an angle of 60 with the bottom of the bevelled edge 58 of the wheel Y also tangent to the line 44. Theface AIIS of the wheel Y extends at an angle to the faces 41 and 48 of the wheels X and Z that lie in the same plane- In Figure 4, I show how the wheels are rotated by means of a motor H. The wheels X, Y and Z have pulleys 49, and 5I, respectively, and these pulleys have a belt 52 passed therearound and also around a motor pulley 53. Idler pulleys 54 are placed between the pulleys 49 and 59, and the pulleys 50 and 5I, so that the same belt can rotate the three pulleys even though the axis of the pulley Y extends at an angle to the axes of the pulleys X and Z. A hand grip 55 is used for moving the grinding head along the slide ways G.

From the foregoing description of the various parts of the device, the operation thereof may be readily understood.

In setting up the saw E in the vise bars I3, a gage, not shown, is used so that the roots of the teeth to be ground in the saw lie in a line that passes through the line 44 shown in Figure 3. This assures the operator that the teeth will be properly ground on the saw. The line 123 is in.- dicated in Figure 8 and this figure schematically shows the angular position of the saw with respect `to the wheels X, Y and Z during the grinding operation. The turntable B is swung in a counter-clockwise direction into the dot-dash line position shown in Figure 1 when the wheels X andY are used for grinding the teeth. The

InFigure 5, the-wheel X is shown with its-bevel The4 grindinghead :is moved -forrfbringing the wheel--X into; contact-With the edge :l when the rotation of the wheel-is clockwise-When lookingat-arrowa Figure'S, and-this will cause-the-wheel--- tofgrind -the edge- With-the grain of the teeth. f

The--wheel--is moved entirely; across the Saw E during-the grinding movement.-

The :operator now--moves-,the grinding-headiso that the `wheel-Y will-'eut --across the saw.4 The beveledge '.58 of-the-wheel---Y lwill grind-the rake side-,ofansadjacent--toot-h J', The wheelfY is rotating in a counter-clockwisel direction, when' looking i at Figure 8, -see arrow b, and therefore thek lower portion -of the Wheel that grinds'the saw will 4be cutting withthe-grain of4 the-saw.- In

actual-practice, the wheel-Y rotates -in a reverse-f' direction to the wheel-X.; It wil-l be seen-from Figure 5 that the edge 58 of the wheel Y will con-- tact only-with the -rakeedge-59 of the tooth-J and will not touch the edge- 51 .of the tooth J,

because the bevel angle-.of the wheel-is less than the -angle between -the teeth In like manner the bevel edge 56 offthe--wheel-VX willvv contact with the edge :5l-of the tooth-J and wil-l not cone tact with the rake edge--Q--of-the tooth: J The faces of the wheels-do not 'contact with any edges of the teeth, becauseA the bevel-of the wheels is less than 60"-- or--about 459.

portant-point-because the grinding action :of-both wheels when contacting with the sawwill be onlyin the direction of thegrain or the saw and-not against the grain.

The set -screw 23fwi1l be adjusted sothat eac-hf time the foot treadle 3--is depressed the saw-'will be advanced the distance of two teeth. -The -de-rtails of the saw-advancing-mechanism have beendescribed and they need-not be repeated. Usually a crown eiTect-is given-toa sawduring vthe grind ing of -the"teeth-. In AFigure 2f the `dot and-dash "s line-ES-along the top ofthe sawis a straight line,

that the ro-w of teeth ground inthe saw will take the -form of an arcfollowing the line 5| rather than take the form of the straight vl-ine- 60.

Reference-to Figure 2 shows-the traveling -hold-- er D positioned at-the right hand ends of the 1 rods I9. As theholder-is advanced along -the rods step-wise, the end bracketsllwillstart to move downwardly along the slightlyinclined rod portions IB, while the other end bracket i2-wi-l1- move upwardly toward the high center :points of the rods. This movementY results in the saw l1." being gradually lowered as it is moved-longie tudinally-along the rods until the end bracket H 2 is positioned midway between-the; bracket yi? of@ theyset-up frame C vand the centi-a1 bracket-E2 .-31

of the set-up frame. When the 'end'- Ior'acket'rl l is thus positioned, the other end: bracketfl'will be positioned midway between the cen-terbracket 62 and the opposite end bracket QNFurthe-r longi: tudinal movement. of the-traveling holder-D totheleft in Figure 2 will cause the yend bracket -I tot the holder to continue to drop, whilefthe vend bracket l2y will continue-to-rse.v The result of these two movements will cause the -saW-E rtohave its right hand portion gradually raised so-f that the grinding wheels-X andy Willgrind-thev iwheels- Y and-Z as shown, bythe'dottedline pos 6 teeth#l ini.;suoh: a /mannerffthati the; row i-'ohzteetlrifi wi-lltbeyin'thezshapeeofxanearcr: Thisggives thez-:i necessary erowneectmo-the row"of:saw-lrteeth.'y

After- ,the saw :has: .been step-wise 5 advancedxf-f;

ethrQushout-its flengthyaridi the; wheels Xsand; Y

have beenfalternately used'forgrinding theibev: i elled edges-' El and z 59onfthez teeth: J andk JZ.' the; -i sawis movedL intoits right-hand position -asA shown i ini-Figure@ and: is Yplaced between tha-grinding.

tion E in Figure 8. The turntable is swung Glocke; wisegtogmove the saw intoithe Anew position.; The two-wheels fY andrZ willnow:begalternately moved-nx? across-ther sawi-.towgrind-g lthe edges of alternate-,-

I, teeth that have notgloeen-v ,groundv in thefprevious; 1;

operation.- f The grinding ,wheel Y wil-1' grindthere rake edge of-the1tooth l and the grindingl .action f, will bei the same direction asfthe'grain oithe, i saw-.1 Toaccomplishthis, fthe motor'- H is rea.r

reversed initsrotationuso that its:1ower-portion that-contacts :with thesaw will be movingrin1 the direction oil the sawblade, note dotted; arrow c. Afterthegrindmg -head F has `been-movediiorv` '-5 arryingrth'e Wheel Y Past the saw E, the'grind- 1 ingrheadis reversedginits movement :for-bringing the grinding wheel `Z into contactwithth'esaws The wheel-Z will be Vrotated in-a counter-clock-:i wisedirection-when :looking at :the arrow-'d init;

:Figure-t8 soqthat its lower edgef-will be moving.;

towardthe sawA as the-wheel passes-it; 'I'hehevelfff--L edge-63 of then grinding wheel-Z will grindthe-zback of 'the saw. tooth edge;correspondingtopthe: f edgegl in Figure/5. The traveling holder D wilif be step-Wise advancedsothat every-other tooth willbe brought into-a position to be contacted by the wheels-Y andZ. The grinding operationcom--czpletes the grinding of theesaw teeth.

If desired, the?` grinding head` F maycarry a With these two additional mechanisms mounted on .thegrinding head,` the-punching., grinding and setting .ofthe saw teeth can be accomplishedfwith the same frnaehine.- Where a different rakecangle'is -t. o' bemade:inf,y thesaw.- the .sliding fway-s G canbe swung about f' theirpivots S19-fand dit into the vdesiredl 'angular position., When -thisposition. is reachedrtha-- clampingbolts-ili and-Mfmay be tightened: I show in Figure 6 the grinding wheels `X and--Y swungntoa differ-ent position forgrin-dingvthe'f teethon --the -saww The operationis iden-tical t-o-V -1 that. already described and no further description',- need--loe---given-r It is -possible togrind'the vteeth` of rip-or crosscu-tsaws -hyV merelychangingthe rake angle-ofthe slide--waysG-and thus changing .a the ang-le of the grinding head F. Since the slide 'ff-- ways-rotate about -thegi-lOVot-"line 35i-'the' 10i/Verf" edges-of-the-giinding wheels and'Z will also- -f pivot about the -same'liner This is ari-important;` feature `of my@ invention. i

I claimt-f l. A saWz-toothfgrinder-comprisinga horizontal-ff` platform;a turntable swingaloly mounted on the platform; a set-:up frametcarriedby the turntabla; a saw, traveling holder'vslidableyon the frame andsupporti-nga saw so-that lits planeis in a vertical" posit-ions theholder moving the saw, through the f vertical /nivotfaxis' of the turntable, a sliding waysf'.T extendingr; transversely across rthe; platform;- bracketsionifthe aplatform for ypivotally support" ing- ;the1sliding1ways; soy that it can be swung about a horizontal axis that passesthrough said vertical axis, @meansfior securingthe sliding. ways in the ldesiredv angular, position; the travelingv eholderl.-

supporting the saw so that the roots of the saw teeth will pass through the horizontal pivot axis of the sliding ways, a saw grinding head slide-ble on the sliding ways and havinggrinding Wheels, the saw engaging portions of the grinding wheels lying in the horizontal pivot axis, and means for rotating the wheels for causing the saw engaging portions to move with lthe grain of the saw when the grinding head is moved for moving the desired wheel across the saw for grinding a tooth edge.

2. A saw tooth grinder comprising a horizontal platform, a turntable swingably mounted on the platform, a set-up frame carried by the turntable, a saw traveling holder slidable on the frame and supporting a saw so that its plane is in a vertical position, the holder moving the saw through the vertical pivot axis of the turntable, a sliding ways extending transversely across the platform, brackets on the platform for pivotally supporting the sliding ways so that it can be swung about a horizontal axis that passes through said vertical axis, means for securing the sliding ways in the desired angular position, the traveling holder supporting the saw so that the roots of the saw teeth will pass through the horizontal pivot axis of the sliding ways, a saw grinding head slidable on the sliding ways and having grinding wheels, the saw engaging portions of the grinding wheels lying in the horizontal pivot axis, and means for rotating the wheels for causing the saw engaging portions to move with the grain of the saw when the grinding head is moved for moving the desired wheel across the saw for grinding a tooth edge, and means for step-wise advancing the saw the distance of two teeth each time the means is actuated, said frame holding the saw at an angle with respect to the sliding ways so that the wheel will bevel the tooth edge contacted.

3. A saw tooth grinder comprising a horizontal platform, a turntable swingably mounted on the platform, a set-up frame carried by the turntable, a saw traveling holder slidable onthe frame and supporting a saw so that its plane is in a vertical position, the holder moving the saw through the vertical pivot axis of the turntable, a sliding ways extending transversely across the platform, brackets on the platform for pivotally supporting the sliding ways so that it can be swung about a horizontal axis that passes through said vertical axis, means for securing the sliding ways in the desired angular position, the traveling holder supporting the saw so that the roots of the saw teeth will pass through the horizontal pivot axis of the sliding ways, a saw grinding head slidable on the sliding ways and having grinding wheels, the saw engaging portions of the grinding wheels lying in the horizontal pivot axis, and means for rotating the wheels for causing the saw engaging portions to move with the grain of the saw when the grinding head is moved for moving the desired wheel across the saw for grinding a tooth edge, and means for step-wise advancing the saw the distance of two teeth each time the means is actuated, said frame holding the saw at an angle with respect to the sliding ways so that the wheel will bevel the tooth edge contacted and Aieans for giving a slight arc in a Vertical plane to gent with a line that parallels the line of movement, means for rotating the wheels in opposite directions so that their lower portions will be moving toward each other, means for supporting a saw blade between the wheels so that the tangent line will cut across the line that coincides with the root of the saw teeth, the bevelled wheel rims beingadapted to alternately grind the two edges forming a root between adjacent teeth, the bevel angle of the wheels being less than 60 which is the angle between adjacent teeth, the axis of one wheel extending at an angle with respect to the axis of the other wheel such that one wheel will contact with only one tooth edge at a time and will grind rwith the grain of the saw.

5. In a saw tooth grinder, horizontally disposed sliding ways, a grinding head movable along the sliding ways, at least two grinding wheels rotatably carried by the grinding head, said wheels having bevelled rims at less than 69 angles whose lower edges lie tangent with a line that parallels the line of movement, means for rotating the' 'wheels in opposite directions so that their lower portions will be moving toward each other, means for supporting a saw blade between the wheels so that the tangent line will cut across the line that coincides with the root of the saw teeth, the bevelled wheel rims -being adapted to alternately grind the two edges forming a root between adjacent teeth, the bevel angle of the wheels being less than 60 which is the angle between adjacent teeth, the axis of one wheel extending at an angle with respect to the axis of the other wheel such that one wheel will contact with only one tooth edge at a time and will grind with the grain of the saw, means for rockably supporting the sliding Ways so that it can pivot about the line that is tangent with the wheel bottoms, whereby the sliding ways can be rocked into positions for causing the wheels to grind the teeth edges at the desired rake angles, and means for securing the sliding ways in adjusted position.

6. In a saw tooth grinder, horizontally disposed sliding ways, a grinding head movable along the sliding ways, at least two grinding wheels rotatably carried by the grinding head, said wheels having bevelled rims at less than a 60 angle whose lower edges lie tangent with a line that parallels the line of movement, means for rotating the wheels in opposite directions so that their lower portions will be moving toward each other, means for supporting a saw blade between the wheels so that the tangent line will out across the line that coincides with the root of the saw teeth, the bevelled wheel rims being adapted to alternately grind the two edges forming a root between adjacent teeth, the axis of one wheel extending at an angle with respect to the axis of the other wheel, the bevel of the wheels being less than 60 angle whereby one wheel will contact with only one tooth edge at a time and will grind with the grain of the saw, and means for adjusting the Saw blade support for holding the saw at the desired angle withrespect to the said tangent line, whereby the wheels will grind the tooth edges at the desired bevel.

7. A saw tooth grinder comprising a horizontally disposed sliding ways, a grinding head slidable along the ways, three bevelled grinding Vwheels carried by the head and arranged in a row so that their lower edges will lie tangent to a line that parallels the sliding ways, the axes of the two end wheels lying in a plane so that the bevelled edges will grind onlyv the back edge of the tooth Vit engages when-the head is moved for causing the vewheel toV contact-with 'f themiddle'wheel causing its bevelled edge to Vgrind only the rakeyedgeof the tooth it engages, the

wheels being spaced apart so that only one wheel 'will contact the sawl at a given time, and means for rotating the wheels so that the saw engaging portionwill ber cutting withthe grain of the saw while contacting the saw.

8. A saw tooth grinder comprising ahorizontally disposed sliding ways, a grinding head slidable along .the .vways, three bevelled grinding wheels carried by the head and arranged in a row so that their rlower-edgesk will lie tangent to a line that parallels the sliding ways, the axes of the two A-end wheels lying in a plane so thatthe bevelled edges will grind only the back edge of the tooth it engages :when the head is` moved for causing the wheel to contact with asaw tooth, the axis of themiddle wheel causing'its bevelled edge to grind only the rake edge ofthe tooth ityengages,- the wheels being-spaced-apart, so that.k onlyn one wheel will contactthe-sawat a given time, and

f means for rotating-thewheels so that the saw enso that their lower edges will lie tangent to a line that parallels the sliding ways, reversible means for rotating the outer wheels in one direction and the center wheel in an opposite direction, the portions of the end Wheels that are tangent with said line, lying in the plane that extends at an angle of 60 with a plane that coincides with the lower bevel portion of the middle wheel that lies tangent to the same line, one end wheel and the center wheel being adapted to straddle a saw and adapted to alternately contact the saw when the head is reciprocated on the sliding ways, said wheelrotating means causing the lower portions of said end wheel and center wheel to rotate toward the saw, the grinding head also being positionable so that the other end wheel and said center wheel will straddle the saW, the head being movable for alternately bringing these wheels into contact with the saw, said wheel rotating means being reversed for causing the last two mentioned wheels to be reversed in their rotation for causing them to grind the saw with the grain.

10. A saw tooth grinder comprising a grinding head, three bevelled grinding wheels rotatably carried by the head and arranged in a row so that the lower edges of the wheels will lie in a straight line, a reversible motor operatively connected to the wheels for rotating the end wheels in the same direction and the center wheel in the opposite direction, the lower bevelled edge of the center wheel making an angle of 60 with the lower bevelled edges of the two end wheels, the apex of the angle coinciding with said line, the wheels being spaced apart so that a saw blade can be received between either end wheel and the center wheel, the bevel of the wheels being less than a 60 angle so that only one tooth edge will be contacted by a wheel at any one time.

11. A saw tooth grinder comprising a grinding head, three bevelled grinding wheels rotatably carried by the head and arranged in a row so that the lower edges of the wheels will lie in a straight xline, a reversible motor operatively connected to the wheels for rotating the lend-wheels in the same direction andthe center whee1 in theoppositedirection, thelower ybevelled v edge of. the center 4, wheel making an angle of60 withthe lower bevgelled edgesv of thetwo endl wheels', the apex of the angle coinciding witllsaid lineg'the wheels being n spaced apart sothat a sawbladecan be received between'eitherjend wheelandthe centerwheel the bevelof; thewheels being less than a60.angle so that only vone vtoothgedge vwill. be contacted by awh'eel at any one time, and sliding ways for slid- 'ably supporting,the grinding. head `with respect to the saw.

*"l2: AY saw tooth grinder .comprising ai grinding v headr-.three bevelled grinding I Wheels` rotatably carried .by the headgand arranged in arow so thattheylower, edges.' of..the1wheels will lie` in a straight line, a reversible motor,operatively` .con-

nected to thewheels for rotating the ,end wheels in the same direetionrand thecenter wheel inthe opposite direction,.tlie. lower bevelled edge of the with said line whereby the wheels will remain tangent to the line during the swinging movement of the sliding ways, and means for securing the sliding ways in adjusted position.

13. A saw tooth grinder comprising a grinding head, three bevelled grinding wheels rotatably carried by the head and arranged in a row so that the lower edges of the wheels will lie in a straight line, a reversible motor operatively connected to the wheels for rotating the end wheels in the same direction and the center wheel in the opposite direction, the lower bevelled edge of the center wheel making an angle of 60 with the lower bevelled edges of the two end wheels, the apex of the angle coinciding with said line, the wheels being spaced apart so that a saw blade can be received between either end wheel and the center wheel, the bevel of the wheels being less than a 60 angle so that only one tooth edge will be contacted by a wheel at any one time and sliding ways for slidably supporting the grinding head with respect to the saw, ibrackets for pivotally supporting the sliding ways at points coinciding with said line whereby the wheels will remain tangent to the line during the swinging movement of the sliding ways, and means for securing the sliding ways in adjusted position, means for supporting the saw so that the roots of the teeth will coincide with the line, said saw supporting means being swingable into angular positions for causing the saw to extend at an angle with respect to the wheels, whereby the Wheels Iwill grind the desired bevel on the tooth edges.

lll. A saw tooth grinder comprising a grinding head, three bevelled grinding wheels rotatably carried by the head and arranged in a row so that the lower edges of the wheels will lie in a straight line, a reversible motor operatively connected to the wheels for rotating the end wheels in the same direction and the center wheel in the opposite direction, the lower bevelled edge of the center wheel making an angle of 60 with the e 1l lower bevelled -edges of the two end Wheels, the apex of the angle coinciding with said line, the wheels being spaced apart so that a saw blade can be received between either end wheel and the center wheel, the bevel of the wheels being less than a 60 angle so that only one tooth edge will be contacted by a wheel at any one time and sliding ways for slidably supporting the grinding head with respect to the saw, brackets for pivotally supporting the sliding ways at points coinciding with said line whereby the wheels will remain tangent tothe line during the swinging movement of the sliding ways, and meansforfsecuring the'sliding ways in adjusted position, means for supporting .the saw so that the roots of the teeth will coincide' with the line, said saw supporting means being swingable into angular positions for causing the sawto extend at an angle with respect to the wheels, whereby the wheels will grind the desired bevel on the tooth edgesand means associated with the saw supporting means forl step-wise advancing the saw two teeth at a time. 15. In a grinder for sharpening teeth of a saw blade, a clamp for supporting a saw, and means MARTIN HQWILBERT.

REFERENCES CITED The following references are of record in the -le of this patent:

UNITED STATES PATENTS Number Name Y Date 1,732,132 Marshall Oct. 15, 1929 378,277 Amesbury Feb. 21, 1888 2,067,179 Elder Jan. 12, 1937 62,705 Tuder Mar. 5, 1867 

